The present invention relates to a method for continuously making and distributing snow or small water droplets, and to a device for carrying out the method.
Downhill skiing is practised by a large number of people all over the world, both by amateurs and by professionals. Downhill disciplines generally require a ground covered by snow and/or ice. However, since the access to snow is highly varying, depending e.g. on the season, the weather etc, attempts have been made to produce artificial snow or ice as a substitute.
Thus, many downhill facilities are equipped with snow guns, i.e. devices for making and distributing snow, or more specifically small water droplets, which in the ambient cold atmosphere freeze into ice crystals. Many such devices are known, all of which operate according to substantially the same principle. According to this principle, a water jet and an air jet are mixed and the mixture is broken up into smaller droplets which on their way to the ground freeze into ice crystals.
The most basic technique for making ice crystals appears to be described in U.S. Pat. No. 2,676,471. In a device disclosed in this publication, water and air are mixed in a plurality of nozzles mounted e.g. on a sled, whereupon the mixture is squeezed out under high pressure through small nozzle orifices and is thus distributed over the piste. Mixture takes place in a chamber located in the front part of the nozzle, the air being caused when passing into the chamber to entrain water fed to an annular gap in the chamber. To form small droplets in the water-air mixture, the chamber has a convex surface on which the entering jet impinges.
For instance, to improve the distribution of the droplets thus formed and to increase efficiency, it is known from U.S. Pat. No. 3,814,319 to mount a device of the type described in U.S. Pat. No. 2,676,471 in the top of a mast having a length of at least 3 m (10 feet).
The device described in CH-PS-529,325 operates substantially according to conventional principles. The device comprises a chamber in the form of a tube, in which water and air are mixed. This mixture is then fed to a nozzle containing a ball which atomizes the mixture before this leaves the nozzle through holes or channels provided therein.
The device known from NO-L-913,205 comprises a chamber for mixing water and air. Moreover, there is provided a means for maintaining a substantially constant pressure in the mixing chamber.
A currently extensively used type of snow gun is the low-pressure snow gun. This type of gun is described in AT-B-393,318 and is based on the principle of using a powerful fan for accelerating and distributing the water-air mixture. As opposed to the above-mentioned devices, which operate according to the high-pressure principle, the water is sprayed into the air stream produced by the fan, thus mixing the water and the air in the fan-induced air stream, and not in a mixing chamber. One advantage of this type of snow gun is that it is considerably more silent in operation than snow guns of the high-pressure type.
Even if the prior-art devices perform satisfactorily in respect of snow making, they suffer from certain drawbacks, of which only some are mentioned here. One of the more serious drawbacks is the high power consumption (kWh/m.sup.3) in connection with snow making.
Another drawback is that, owing to limited efficiency and distributing capacity, a relatively large number of devices are normally required for covering e.g. a piste for downhill skiing.
Moreover, the nozzles of both the high-pressure and the low-pressure type are liable to icing, which often results in clogging of the nozzles. Thus, these devices must be constantly attended to, which requires much labour.